driver: misc: Add MU and S400 API to communicate with Sentinel

Add MU driver and S400 API. Need enable MISC driver to work

Signed-off-by: Ye Li <ye.li@nxp.com>
diff --git a/drivers/misc/imx8ulp/Makefile b/drivers/misc/imx8ulp/Makefile
new file mode 100644
index 0000000..1d79241
--- /dev/null
+++ b/drivers/misc/imx8ulp/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+obj-y += s400_api.o imx8ulp_mu.o